For the first time in state history, an independent group of citizens has redrawn California's political districts, approving a set of maps Monday that are expected to help Democrats garner more power in the solidly blue state.

Even before the 14-member Citizens Redistricting Commission approved the boundaries, however, the prospect of a lawsuit or a referendum challenging the new lines was raised by Republican critics, and one GOP commissioner publicly charged that the new maps violate state law.

If the maps survive any legal or ballot box challenges, they will remain in place for the next decade, and could give Democrats the chance to seize a two-thirds majority in the state Senate. The new boundaries may also lead to fewer Republican members of Congress. California has 53 congressional representatives; currently, Republicans hold 19 of those seats.

The overwhelming majority of commissioners voted in favor of the new lines, including Chairman Vincent Barabba, a Republican from Capitola (Santa Cruz County), who said that in past years when lawmakers drew their own boundaries, the two major parties often struck deals to protect incumbent lawmakers.

He noted that since 2002, California has held 765 congressional and legislative elections, yet only five seats have changed parties, and predicted that the true impact of the commission and new maps won't be felt for several years. He urged critics of the new maps to look at the "totality" of the state, rather than only their district.

Voters may have another chance to weigh in: In a statement, California Republican Party Chairman Tom Del Beccaro said a referendum challenging the state Senate lines and possibly the congressional boundaries "will be filed" and that the Republican Party will "wholeheartedly support those efforts when they come about."

Ward charged that the commission broke the law by splitting African American voters among several congressional districts in Los Angeles County, and accused the group of inconsistency when considering other types of communities.

The commission - made up of five Republicans, five Democrats and four independents - was charged with drawing the political boundaries without factoring in incumbents or party registration figures.

Much of the controversy has focused on Southern California districts. In the Bay Area, the new boundaries are not expected to result in significant political changes, though at least one lawmaker will have to move: Democratic Rep. Jerry McNerney's district is shifting east, into the more conservative San Joaquin County, and McNerney's Pleasanton home will no longer be part of that district. McNerney has said he plans to move to the new district.

The congressional district that includes Marin County will now run all the way to the Oregon border, and San Francisco will be home to only one state Senate district, instead of two. Commissioner Maria Blanco, a Democrat from Los Angeles, also expressed reservations about the city of Martinez being separated from the rest of Contra Costa County in the congressional Fifth District, which spreads north into Napa County.